Make SkGLContext's FBO creation more robust (allows test apps to run on Intel GPUs)

Review URL: http://codereview.appspot.com/5647059/



git-svn-id: http://skia.googlecode.com/svn/trunk@3157 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/gpu/SkGLContext.h b/include/gpu/SkGLContext.h
index f92a770..542d1bb 100644
--- a/include/gpu/SkGLContext.h
+++ b/include/gpu/SkGLContext.h
@@ -9,6 +9,7 @@
 #define SkGLContext_DEFINED
 
 #include "GrGLInterface.h"
+#include "SkString.h"
 
 /**
  * Create an offscreen opengl context with an RGBA8 / 8bit stencil FBO.
@@ -31,6 +32,8 @@
 
     virtual void makeCurrent() const = 0;
 
+    bool hasExtension(const char* extensionName) const;
+
 protected:
     /**
      * Subclass implements this to make a GL context. The returned GrGLInterface 
@@ -46,6 +49,7 @@
     virtual void destroyGLContext() = 0;
 
 private:
+    SkString fExtensionString;
     GrGLuint fFBO;
     const GrGLInterface* fGL;
 };